JPH11246768A - Rapid-curing alkoxyl-functional spontaneously vulcanizable composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rapid-curing alkoxyl-functional spontaneously vulcanizable composition by mixing a polymer containing alkoxysilyl chain stopping groups with a tetraalkoxytitanium compound, a filler, and an alkoxysilane. SOLUTION: This composition contains the following components A to D and cures in the presence of water: (A) a polymer having at least 1.2, on the average per molecule, alkoxysilyl chain stopping groups of the formula: -SiR<1> x (OR)3-x (wherein each R is methyl or ethyl; and x is 0 or 1); (B) a tetraalkoxytitanium compound of the formula: Ti(OR<2> )y (OR<3> )4-y (each R<2> is a tert. alkyl or 2,4-dimethyl-3-pentyl; each R<3> is a 1-6C alkyl; and y is 3-4 on the average); (C) a filler having a hydroxyl content ascribable to adsorbed water or the like; and (D) an alkoxysulane of the formula: Rz <4> Si(OR<5> )4-z (wherein each R<4> is a 1-12C alkyl or an alkenyl; each R<5> is methyl or ethyl; and z is 1 or 2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an alkoxysilane which comprises a polymer having an average of at least 1.2 alkoxysilyl chain terminators per molecule, a tetraalkoxytitanium compound, a filler and an alkoxysilane, which cures in the presence of moisture. Functional vulcanization (RTV) composition. Addition of these components in amounts that satisfy the defined molar ratios provides a fast cure, alkoxy-functional RTV composition.

[0002]

BACKGROUND OF THE INVENTION Polyorganosiloxane compositions that cure to an elastic material at room temperature are well known. Such a composition is obtained by mixing a polysiorganosiloxane having a reactive group such as a silanol group with a silane crosslinking agent, for example, alkoxysilane, acetoxysilane, oximosilane or aminosilane. Compositions composed of these components cure upon exposure to moisture in the air at room temperature.

[0003] The use of moisture-curable compositions as sealants is well known. For some applications, it is necessary to use a sealant that cures quickly. Fast-curing sealant compositions include silicone sealant compositions that generate acetic acid, ketoxime or amine as a by-product during curing. These by-products have an unpleasant odor and corrode sensitive metals or plastics. Therefore, the use of other compositions that do not have these properties is advantageous. An alternative to these compositions is an alkoxy-functional RTV composition that generates alcohol during curing.

[0004]

However, alkoxy-functional RTV compositions containing tetraalkoxytitanium compounds, such as tetraisopropoxytitanium and tetra-n-butoxytitanium, cure slowly and are tack-free for less than 60 minutes. Few have a time (TFT). Therefore, these compositions are not suitable for applications requiring rapid curing. We have discovered that the addition of certain tetraalkoxytitanium compounds, such as tetratertiary alkoxytitanium compounds, in amounts that satisfy a given molar ratio allows for a rapidly curing alkoxy-functional RTV composition. .

[0005] It is an object of the present invention to produce a fast cure alkoxy-functional RTV composition.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a polymer having an average of at least 1.2 alkoxysilyl chain terminating groups per molecule, a tetraalkoxytitanium compound, a filler and an alkoxysilane (each component having a defined molar ratio). ), Which cures in the presence of moisture to provide a fast-curing alkoxy-functional RTV composition.

The fast-curing alkoxy-functional RTV compositions of the present invention that cure in the presence of moisture include: (A) Formulas -SiR1x (OR) 3-x (VII), where each R is methyl, ethyl, n Independently selected from the group consisting of -propyl, isopropyl, n-butyl, sec-butyl and isobutyl; R1 is selected from methyl or ethyl; x is 0 or 1). A polymer having 2 alkoxysilyl chain terminators;

(B) Formula Ti (OR2) y (OR3) 4-
y (V) (wherein each R2 is a tertiary alkyl group or 2,4
Independently selected from -dimethyl-3-pentyl; each R3 is independently selected from alkyl groups having 1 to 6 carbon atoms; y
Is an average value of 3 to 4).

(C) a filler having a hydroxyl content derived from covalently bonded hydroxyl groups, adsorbed water, or both covalently bonded hydroxyl groups and adsorbed water; and

(D) The formula R4zSi (OR5) 4-z (V
I) wherein each R4 is independently selected from an alkyl group having 1 to 12 carbon atoms and an alkenyl group having 1 to 12 carbon atoms; each R5 is independently selected from methyl or ethyl; Alkoxysilane described by 1 or 2);

The components (A), (B), (C) and (D) have the following molar ratio (I) of at least 0.9 and a molar ratio (II) of 0.15 to 0.5. It is added in an amount such that it is in the range of 6:

[0012]

[0013]

EXAMPLES Component (A) comprises a polymer having an average of at least 1.2 alkoxysilyl chain terminating groups per molecule described by formula (VII). The polymer may be linear or branched and may be a homopolymer, a copolymer or a terpolymer. The polymer is a mixture of single or heterogeneous polymers, providing a polymer having an average of at least 1.2 alkoxysilyl chain termination groups per molecule.

The repeating units of the polymer of component (A) may be organic groups such as oxyalkylene units or, preferably, of the formula R9s
SiO (4-s) / 2 (wherein each R9 has 1 carbon atom)
-6 independently selected from the group consisting of alkyl groups, phenyl, and fluorinated alkyl groups, wherein s is 0, 1, or 2). Examples of the alkyl group described by R9 include methyl, ethyl, propyl, butyl and hexyl. Examples of the fluorinated alkyl group described by R9 include 3,3,3-trifluoropropyl. Desirable polymers of component (A) are of the formula
(R9sSiO (4-s) / 2) f- (wherein each R9 is methyl, s is 2 and f is the component (A) at 25C)
0.5 to 3000 Pa · s, preferably 5 to 150 P
a value having a viscosity in the range of a · s).

The polymer of the component (A) is represented by the formula (VII): -SiR1x (OR) 3-x (wherein R, R1
And x is as defined above) on average per molecule of at least 1.2 alkoxysilyl chain terminators. Each R in the preferred embodiment is independently selected from methyl or ethyl, and x is 0.

In a further preferred embodiment, the spacer group Z is attached to the Si atom of the alkoxysilyl chain terminator, and each Z is a divalent carbon atom containing no aliphatic unsaturation and having 2 to 18 carbon atoms. Combinations of hydrogen or divalent hydrocarbon groups, and formulas

[0017]

Embedded image (Wherein R 9 is as defined above; each G is a divalent hydrocarbon group containing no aliphatic unsaturation and having 2 to 18 carbon atoms; c is a total number of 1 to 6). Independently selected from the group consisting of siloxane segments. Examples of divalent hydrocarbon groups describing Z and G are ethylene,
Alkylene groups such as methylmethylene, propylene, butylene, pentylene and hexylene; and allylene groups including phenylene;
Particularly, ethylene is desirable. In these preferred embodiments, each Z is independently selected from a combination of an alkylene group or a divalent hydrocarbon group and a siloxane segment, as described above, each G is an alkylene, preferably ethylene; each R9 Is methyl; c is 1. More preferably, each Z is an alkylene group, optimally ethylene.

The polymer of component (A) must have an average of at least 1.2, preferably 1.5, alkoxysilyl chain termination groups per molecule. Because the polymer of component (A) must have an average of at least 1.2 alkoxysilyl chain terminators per molecule, some polymers contain another type of chain terminator. This other type of chain terminator has a CH2 =
Consisting of an organosilyl chain terminator selected from CH-SiR92- or R63-Si-, wherein R9 is as defined above and R6 is independently selected from methyl, ethyl, or vinyl. Examples of organosilyl chain terminators include trimethylsilyl, triethylsilyl, vinyldimethylsilyl and vinylmethylphenylsilyl.

Polydiorganosiloxanes useful in the present invention, as well as crosslinkers, fillers and other optional ingredients useful in alkoxy-functional RTV silicone sealant compositions are well known and are disclosed in US Pat. No. 3,151,099. ;
3,161,614; 3,175,993; 3,33
4,067; 4,871,827; 4,898,910
And 4,956,435.

The polydiorganosiloxane of component (A) is exemplified by the disclosure of US Pat. No. 3,161,614 and has the formula (I)

[0021]

Embedded image Or a mixture of a polydiorganosiloxane described by formula (I) and a compound of formula (II)

[0022]

Embedded image Wherein R, R1, R6, R9x and f are as described above.

Desirable polydiorganosiloxanes of component (A) are described in US Pat. Nos. 3,175,993 and 4,8
71,827, including those described by formula (III)

[0024]

Embedded image (R, R1, R9, Z, x and f in the formula are as described above.

Other desirable components (A) useful in the present invention
Are disclosed in US Pat. No. 4,898,910 and polyorganosiloxanes described by formula (III)
A mixture of polydiorganosiloxanes described by formula (IV):

[0026]

Embedded image (In the formula, R, R1, R9, Z, x, and f are as described above.)

When component (A) is a mixture of the polydiorganosiloxanes described by formulas (III) and (IV), typically the polysiorganosiloxanes described by formula (IV) comprise the component (A) 40% or less of the chain terminating group of
Desirably it is present in an amount such that no more than 25% is organosilyl chain terminating groups. The most preferred polymer of component (A) of the present invention is the polymer described by formula (III).

Component (A) is a compound of the formula (VII)
Also included are organic polymers having an average of 1.2 alkoxysilyl chain terminators per molecule described by x (OR) 3-x, where R, R1 and x are as defined above.
The organic polymer within the scope of component (A) is a spacer-group -Z (Z
Is as described above). One class of organic polymers useful in the present invention is the polyoxyalkylenes described in U.S. Pat. No. 5,403,881, which averages at least one polymer per molecule described by formula (VII). No. 2 polyoxyalkylene polymers having alkoxysilyl chain terminating groups and methods for preparing these polymers.

The amount of component (A) useful in the alkoxy-functional RTV compositions of the present invention depends on the molar ratio (I) described below.
And (II) will depend on the amount of other components added to satisfy. Typically, however, component (A) has 3 parts based on the total weight of the alkoxy-functional RTV composition.
0-85% by weight, preferably 40-65% by weight.

The alkoxy-functional RTV composition of the present invention comprises a Ti (OR2) y (OR3) 4-y of average formula (V)
Wherein each R is independently selected from a tertiary alkyl group or 2,4-dimethyl-3-pentyl; each R3 is independently selected from an alkyl group having 1 to 6 carbon atoms; Is an average value of from 4 to 4].

Examples of the tertiary alkyl group represented by R2 include tertiary butyl and tertiary amyl. Preferably, each R2 is selected from a tertiary alkyl group, more preferably independently selected from a tertiary butyl group or a tertiary amyl group.

When the number of carbon atoms represented by R3 is 1 to 6
Examples of alkyl groups of include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and hexyl.

In formula (VI), Y is an average value of 3 to 4, preferably 3.4 to 4, and most preferably 3.6 to 4.

The amount of component (B) useful in the alkoxy-functional RTV compositions of the present invention is based on the amount of other components added to satisfy the molar ratios (I) and (II) described below. Dependent. However, typically component (B) is present in an amount ranging from 0.1 to 0.1% based on the total weight of the alkoxy-functional RTV composition.
It is added in an amount of 5% by weight, desirably 0.5 to 3.0% by weight. The tetraalkoxytitanium compound is a single kind or a mixture of two or more kinds.

The alkoxy-functional RTV compositions of the present invention comprise a filler (c) having a hydroxyl content derived from covalently bonded hydroxyl groups, adsorbed water or both covalently bonded hydroxyl groups and adsorbed water. The term "covalently bonded hydroxyl group" as used herein means a hydroxyl group that is covalently bonded to a filler and used for a reaction. The term "adsorbed water" refers to the associated water on the surface of the filler utilized in the reaction and water from within the filler becoming available for the reaction.

Certain fillers have only adsorbed water and no covalent hydroxyl groups. However, many fillers have both covalent hydroxyl groups and adsorbed water, eg, untreated fumed silica fillers. The hydroxyl filler of the filler can be changed by drying the filler and / or pretreating the filler with a hydrophobic agent such as hexamethyldisilazane.

The filler is chosen from those known to be useful in alkoxy-functional RTV sealants. These fillers are ground, precipitated and colloidal calcium carbonate (which are untreated or treated with stearic acid or stearate); reinforcing silicas such as fumed silica, precipitated silica and hydrophobized silica. Crushed quartz, crushed quartz, alumina, aluminum hydroxide, titanium dioxide, diatomaceous earth, iron oxide, carbon black and graphite. Silica and calcium carbonate are particularly useful, and a mixture of fumed silica and treated ground calcium carbonate is desirable.

[0038] The amount of filler useful in the alkoxy-functional RTV composition depends on the viscosity, thixotropy, color and UV.
Provides the necessary properties of the uncured composition, such as protection. The amount of filler also depends on the required cured physical properties such as tensile strength, elongation and durometer.

The amount of filler useful in the alkoxy-functional RTV compositions of the present invention depends on the amount of other ingredients added, such that the molar ratios (I) and (II) described below are satisfied.
It also depends on the hydroxyl content of the particular filler used. However, typically the filler is added in an amount of 5-70% by weight, preferably 20-60% by weight, based on the total weight of the alkoxy-functional RTV composition.
The filler may be a single type or a mixture of two or more types.

The alkoxy-functional RTV composition of the present invention has the formula (VI): R4zSi (OR5) 4-
z wherein each R4 is independently selected from an alkyl group having 1 to 12 carbon atoms or an alkenyl group having 1 to 12 carbon atoms, and each R5 is independently selected from methyl or ethyl;
Is 1 or 2.].

The alkyl group having 1 to 12 carbon atoms represented by R4 includes methyl, ethyl, isobutyl, hexyl, octyl and dodecyl. The alkenyl group having 1 to 12 carbon atoms represented by R4 includes vinyl, allyl and butadienyl. Desirably, each R4 is independently selected from the group consisting of methyl, ethyl, isobutyl and vinyl, with methyl being optimal. The subscript Z in Formula (IV) is 1 or 2, and 1 is desirable.

Examples of useful alkoxysilanes are methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, ethyltrimethoxysilane, octyltriethoxysilane,
Including dimethyldimethoxysilane, vinylmethyldimethoxysilane, dimethyldiethoxysilane, isobutyltrimethoxysila and ethylmethyldiethoxysilane.
Partial hydrolysates of these alkoxysilanes can also be used in the composition. Preferred alkoxysilanes include methyltrimethoxysilane and dimethyldimethoxysilane.

The amount of alkoxysilane useful in the alkoxylable RTV compositions of the present invention depends on the amounts of other components added to satisfy the molar ratios (I) and (II) described below. . However, typically, the alkoxysilane is added in an amount ranging from 0.1 to 10% by weight, preferably from 0.1 to 3% by weight, based on the total weight of the alkoxy-functional RTV composition. The alkoxysilanes can be used alone or as a mixture of two or more.

The molar ratio (I) is a value (sum) obtained by adding a mole of an alkoxysilane (component (D)) to a mole of a tetraalkoxytitanium compound (component B) and is a mole of the hydroxyl content in the filler (D). Defined as the divided value. Excellent storage stability is obtained when the inventive RTV composition has a molar ratio (I) of at least 0.9.
The molar ratio (I) of the preferred embodiment is in the range of 0.9-5, more preferably 1-3. Excellent stability is obtained when the molar ratio (I) is 5 or more, but other considerations make these compositions undesirable. For example,
Since the alkoxysilane and tetraalkoxysilane compounds are both molecules in molar ratio (I), having a ratio of 5 or more means increasing one or both of these components. However, increasing the amount of alkoxysilane decreases the cure rate, and increasing the amount of the tetraalkoxytitanium compound increases the cost of the composition and reduces the stability of the hydrolysis. Although the hydroxyl content in the filler can be reduced to lower the molar ratio denominator, it is not practical to reduce the hydroxyl content of the filler below a certain level.

The molar ratio (II) is obtained by adding the mole of the tetraalkoxytitanium compound (component B) to the mole of the alkoxysilane (component (D)) and the mole of the alkoxysilyl chain group in the polymer (component (A)). Is defined as the value divided by the sum The RTV composition of the present invention has at least 0.15
When the molar ratio (II) of the RTV composition is excellent, the tack free time is obtained, and the RTV composition cures quickly. The molar ratio (II) in the preferred embodiment is in the range of 0.2 to 0.6, more preferably 0.3 to 0.595. R of the present invention
Although TV compositions cure rapidly when the molar ratio (II) is greater than 0.6, other considerations make these compositions less desirable. For example, increasing the amount of the tetraalkoxytitanium compound increases the cost of the composition and reduces the stability of the hydrolysis. Moreover, the composition has a molar ratio (I
When I) is 0.6 or more, the composition rapidly cures, so that the working time after application of the composition is extremely limited, and the use of an automated robotic device is required.

The other ingredients commonly used in alkoxy-functional RTV compositions, such as adhesion promoters, rheology additives, fungicides, colorants, pigments and plasticizers, determine the ability of the composition to cure. It can be added initially or on storage provided that it does not interfere with the storage or reduce other necessary properties.

If the organofunctional trialkoxysilanes are used as adhesion promoters and their amounts are such that the molar ratio of the organofunctional trialkoxysilane is significantly higher with respect to the moles of alkoxysilane added, the molar ratio (I It is desirable to include the moles of such adhesion promoters as part of the moles of alkoxysilane in the determination of) and (II).

The alkoxy-functional RTV compositions of the present invention cure quickly. These results occur when the RTV composition consists of the tetraalkoxytitanium compound described by formula (V) and the molar ratios (I) and (II) are satisfied.

The present invention is further described by the following examples. “Parts” in the examples means parts by weight (indicated by “pbw”), and the viscosity was measured at 25 ° C. Me represents methyl, Et represents ethyl, “AS linkage” represents an alkoxysilyl linkage group, Ot-Bu represents tertiary butoxy, OnBu represents normal butoxy, OiP
r represents isopropoxy.

Component polymer used in Examples = Formula (where f has an average such that the viscosity of the polymer is 20 Pa · s)

[0051]

Embedded image Polydimethylsiloxane Titanium 1 = Average Formula Ti (Ot-Bu) 3.6 (OiP
r) mixture of titanium molecules having 0.4 titanium 2 = Ti (OiPr) 4 titanium 3 = average formula Ti (OnBu) 3.72 (OiP
r) mixture of titanium molecules with 0.28 titanium 4 = average formula Ti (Ot-Am) 3.92 (OiP
r) Mixture of titanium molecules having 0.08 Alkoxysilane 1 = methyltrimethoxysilane Alkoxysilane 2 = dimethyldimethoxysilane Silica filler = Fume having a surface area of 150 m 2 / g and an adsorbed water content of 0.6% by weight Silica GRD CaCO3 = Pulverized calcium carbonate PPT CaCO3 = average particle size 2-3 μm, surface-treated with stearic acid, adsorbed water content of 0.05% by weight = surface area of about 22 m2 / g, surface-treated with stearic acid And precipitated calcium carbonate skin over time (SOT) having an adsorbed water content of 0.4% by weight

The skin overtime was 25 ° C and 5 ° C.
It is defined as the time required for the curing material to form a tack free surface film when exposed to atmospheric conditions at 0% relative humidity. The skin over time is measured by contacting the fingertip with the surface of the material and slowly pulling the fingertip apart. Skin over time is the time until the sample no longer adheres to the fingertip. The time is recorded in minutes.

Tack-Free Time (TFT) Tack-free time is defined as the time required to form a tack-free surface film, but this test uses contact of a polyethylene film to measure tack-free properties. A clean polyethylene strip is applied to the test surface with light fingertip pressure. The strip is then removed from one end by gently pulling it straight up. The tack free time is the time until the strip cleanly leaves the sample. The test is performed under atmospheric conditions at 25 ° C. and 50% relative humidity. The tack free time is stated in minutes.

Examples 1 to 4 Four alkoxy-functional RTV sealant compositions were each prepared using the ingredients shown in Table 1 under moisture blocking conditions. The compositions were prepared by first adding the alkoxysilane and titanium compound to the polymer, mixing, adding the filler, mixing and drawing a vacuum to remove entrained air. The moles of the groups and components are RT
100 g of V sealant composition and Table 1
In parentheses below the weight parts. In this specification, the defined molar ratios (I) and (II) have been determined using the molar values given. The alkoxy-functional RTV sealant composition was stored in a sealed container protected from atmospheric moisture. Initial tests were performed after storage at 25 ° C. for 7 days. The samples were then aged at 50 ° C. for a further 7 days before retesting. Cure times were tested as described above, and the results are shown in Table 1. Examples 1 and 4 were initially and 50 ° C. using titanium 1 and titanium 4, respectively, as compared to SOT and TFT obtained using titanium 2 and titanium 3 outside the scope of the present invention. Indicates excellent SOF and TFT after storage for one week.

[0055]

Table 1-Use of different tetraalkoxy titanium compounds

Examples 5 to 9 RTV containing titanium 1 in the same manner as in Examples 1 to 4
Sealant compositions were prepared and tested. Those ingredients,
The amounts and the properties measured are shown in Table 2. Comparative Examples 5 and 7
Indicates the criticality at the lower end of the molar ratios (I) and (II) of the fast curing composition and the storage stable composition.

[0057]

Table 2-Compositions containing titanium 1 in various molar ratios

Examples 10-11 RTV containing titanium 4 in the same manner as in Examples 1-4
Sealant compositions were prepared and tested. Those ingredients,
The amounts and the properties measured are shown in Table 3. Comparative Example 10 shows the criticality at the lower end of the molar ratio (II) of the fast-curing composition.

[0059]

Table 3-Compositions containing titanium 4 in various molar ratios

Examples 12-15 RTV sealant compositions were prepared and tested in the same manner as in Examples 1-4. The components, amounts and measured properties are shown in Table 4. Example 14 shows excellent cure rates using different fillers. Comparative Examples 12 and 13 show the lower criticality of the molar ratios (I) and (II) for cure speed using this different filler. Example 15
Indicates that a fast-curing composition is obtained using an alkoxysilane having an alkoxy group.

[0061]

Table 4-Action of different fillers or alkoxysilanes

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[Procedure amendment]

[Submission date] February 2, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Title: Rapid curing, alkoxy-functional natural vulcanizing composition

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an alkoxysilane which comprises a polymer having an average of at least 1.2 alkoxysilyl chain terminators per molecule, a tetraalkoxytitanium compound, a filler and an alkoxysilane, which cures in the presence of moisture. Functional vulcanization (RTV) composition. Addition of these components in amounts that satisfy the defined molar ratios provides a fast cure, alkoxy-functional RTV composition.

[0002]

BACKGROUND OF THE INVENTION Polyorganosiloxane compositions that cure to an elastic material at room temperature are well known. Such a composition is obtained by mixing a polysiorganosiloxane having a reactive group such as a silanol group with a silane crosslinking agent, for example, alkoxysilane, acetoxysilane, oximosilane or aminosilane. Compositions composed of these components cure upon exposure to moisture in the air at room temperature.

[0003] The use of moisture-curable compositions as sealants is well known. For some applications, it is necessary to use a sealant that cures quickly. Fast-curing sealant compositions include silicone sealant compositions that generate acetic acid, ketoxime or amine as a by-product during curing. These by-products have an unpleasant odor and corrode sensitive metals or plastics. Therefore, the use of other compositions that do not have these properties is advantageous. An alternative to these compositions is an alkoxy-functional RTV composition that generates alcohol during curing.

[0004]

However, alkoxy-functional RTV compositions containing tetraalkoxytitanium compounds, such as tetraisopropoxytitanium and tetra-n-butoxytitanium, cure slowly and are tack-free for less than 60 minutes. Few have a time (TFT). Therefore, these compositions are not suitable for applications requiring rapid curing. We have discovered that the addition of certain tetraalkoxytitanium compounds, such as tetratertiary alkoxytitanium compounds, in amounts that satisfy a given molar ratio allows for a rapidly curing alkoxy-functional RTV composition. .

[0005] It is an object of the present invention to produce a fast cure alkoxy-functional RTV composition.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a polymer having an average of at least 1.2 alkoxysilyl chain terminating groups per molecule, a tetraalkoxytitanium compound, a filler and an alkoxysilane (each component having a defined molar ratio). ), Which cures in the presence of moisture to provide a fast-curing alkoxy-functional RTV composition.

The fast-curing alkoxy-functional RTV composition of the present invention, which cures in the presence of moisture, comprises: (A) a formula -SiR ¹ _x (OR) _3-x (VII), wherein each R is methyl, ethyl , N-propyl, isopropyl, n-butyl, sec-butyl and isobutyl, independently selected; R ¹ is selected from methyl or ethyl; x is 0 or 1). A polymer having at least 1.2 alkoxysilyl chain terminators;

(B) Formula Ti (OR ² ) _y (OR ³ )
_4-y (V) wherein each R ² is independently selected from a tertiary alkyl group or 2,4-dimethyl-3-pentyl; each R ³ is selected from an alkyl group having 1 to 6 carbon atoms. Independently selected; y is an average value of 3 to 4);

(C) a filler having a hydroxyl content derived from covalently bonded hydroxyl groups, adsorbed water, or both covalently bonded hydroxyl groups and adsorbed water; and

(D) The formula R ⁴ _z Si (OR ⁵ ) _4-z (V
I) wherein each R ⁴ is independently selected from an alkyl group having 1 to 12 carbon atoms and an alkenyl group having 1 to 12 carbon atoms; each R ⁵ is independently selected from methyl or ethyl; Z is 1 or 2);

The components (A), (B), (C) and (D) have the following molar ratio (I) of at least 0.9 and a molar ratio (II) of 0.15 to 0.5. It is added in an amount such that it is in the range of 6:

[0012]

[0013]

EXAMPLES Component (A) comprises a polymer having an average of at least 1.2 alkoxysilyl chain terminating groups per molecule described by formula (VII). The polymer may be linear or branched and may be a homopolymer, a copolymer or a terpolymer. The polymer is a mixture of single or heterogeneous polymers, providing a polymer having an average of at least 1.2 alkoxysilyl chain termination groups per molecule.

The repeating units of the polymer of component (A) can be organic groups such as oxyalkylene units or, preferably, of the formula R ⁹ s
SiO _{(4-s) / 2} (wherein each R ⁹ has 1 carbon atom)
-6 independently selected from the group consisting of alkyl groups, phenyl, and fluorinated alkyl groups, wherein s is 0, 1, or 2). Examples of the alkyl group described by R ⁹ include methyl, ethyl, propyl, butyl and hexyl. Examples of the fluorinated alkyl group described by R ⁹ include 3,3,3-trifluoropropyl. Desirable polymers of component (A) are of the formula
(R ⁹ _s SiO _{( 4-s) / 2)} f- (wherein each R ⁹ is methyl, s is 2, and f is the component (A) at 25 ° C.)
0.5 to 3000 Pa · s, preferably 5 to 150 P
a value having a viscosity in the range of a · s).

The polymer of the component (A) is represented by the formula (VII): —SiR ¹ _x (OR) _{3- x} (wherein R and R ¹
And x is as defined above) on average per molecule of at least 1.2 alkoxysilyl chain terminators. Each R in the preferred embodiment is independently selected from methyl or ethyl, and x is 0.

In a further preferred embodiment, the spacer group Z is attached to the Si atom of the alkoxysilyl chain terminator, and each Z is a divalent carbon atom containing no aliphatic unsaturation and having 2 to 18 carbon atoms. Combinations of hydrogen or divalent hydrocarbon groups, and formulas

[0017]

Embedded image (Wherein R ⁹ is as defined above; each G is a divalent hydrocarbon radical containing no aliphatic unsaturation and having 2 to 18 carbon atoms; c is a total number of 1 to 6) Independently selected from the group consisting of the siloxane segments described. Examples of divalent hydrocarbon groups describing Z and G are ethylene,
Alkylene groups such as methylmethylene, propylene, butylene, pentylene and hexylene; and allylene groups including phenylene;
Particularly, ethylene is desirable. In these preferred embodiments, each Z is independently selected from a combination of an alkylene group or a divalent hydrocarbon group and a siloxane segment, as described above, each G is an alkylene, preferably ethylene; each R ⁹ is methyl; c is 1. More preferably, each Z is an alkylene group, optimally ethylene.

The polymer of component (A) must have an average of at least 1.2, preferably 1.5, alkoxysilyl chain termination groups per molecule. Because the polymer of component (A) must have an average of at least 1.2 alkoxysilyl chain terminators per molecule, some polymers contain another type of chain terminator. This other type of chain terminator has a CH ₂ ＝
^CH-SiR _{9 2} - or ^R ₆ 3 -Si- (as defined above ^{R 9} in the formula, and ^{R 6} is methyl, ethyl, or choose from vinyl independently) from organosilyl chain termination groups selected from Become. Examples of organosilyl chain terminators include trimethylsilyl, triethylsilyl, vinyldimethylsilyl and vinylmethylphenylsilyl.

Polydiorganosiloxanes useful in the present invention, as well as crosslinkers, fillers and other optional ingredients useful in alkoxy-functional RTV silicone sealant compositions are well known and are disclosed in US Pat. No. 3,151,099. ;
3,161,614; 3,175,993; 3,33
4,067; 4,871,827; 4,898,910
And 4,956,435.

The polydiorganosiloxane of component (A) is exemplified by the disclosure of US Pat. No. 3,161,614 and has the formula (I)

[0021]

Embedded image Or a mixture of a polydiorganosiloxane described by formula (I) and a compound of formula (II)

[0022]

Embedded image Wherein R, R ¹ , R ⁶ , R ⁹ x and f are as described above.

Desirable polydiorganosiloxanes of component (A) are described in US Pat. Nos. 3,175,993 and 4,8
71,827, including those described by formula (III)

[0024]

Embedded image (R, R ¹ , R ⁹ , Z, x and f in the formula are as described above.

Other desirable components (A) useful in the present invention
Are disclosed in US Pat. No. 4,898,910 and polyorganosiloxanes described by formula (III)
A mixture of polydiorganosiloxanes described by formula (IV):

[0026]

Embedded image (In the formula, R, R ¹ , R ⁹ , Z, x, and f are as described above.)

When component (A) is a mixture of the polydiorganosiloxanes described by formulas (III) and (IV), typically the polysiorganosiloxanes described by formula (IV) comprise the component (A) 40% or less of the chain terminating group of
Desirably it is present in an amount such that no more than 25% is organosilyl chain terminating groups. The most preferred polymer of component (A) of the present invention is the polymer described by formula (III).

[0028] Component (A), -SiR ¹ of formula (VII)
_{x (OR) 3-x (} R in the formula, R ¹ and x are as defined above) including the organic polymer having an alkoxysilyl chain termination groups per molecule average of 1.2 as described by.
The organic polymer within the scope of component (A) is a spacer-group -Z (Z) bonded to the Si atom of the alkoxysilyl chain terminator.
Is as described above). One class of organic polymers useful in the present invention is the polyoxyalkylenes described in U.S. Pat. No. 5,403,881, which averages at least one polymer per molecule described by formula (VII). No. 2 polyoxyalkylene polymers having alkoxysilyl chain terminating groups and methods for preparing these polymers.

The amount of component (A) useful in the alkoxy-functional RTV compositions of the present invention depends on the molar ratio (I) described below.
And (II) will depend on the amount of other components added to satisfy. Typically, however, component (A) has 3 parts based on the total weight of the alkoxy-functional RTV composition.
0-85% by weight, preferably 40-65% by weight.

The alkoxy-functional RTV composition of the present invention comprises Ti (OR ² ) _y (OR ³ ) _{4-y of} average formula (V)
Wherein each R is independently selected from a tertiary alkyl group or 2,4-dimethyl-3-pentyl; each R3 is independently selected from an alkyl group having 1 to 6 carbon atoms; Is an average value of from 4 to 4].

Examples of the tertiary alkyl group represented by R ² include tertiary butyl and tertiary amyl. Preferably, each R ² is selected from a tertiary alkyl group, more preferably independently selected from a tertiary butyl group or a tertiary amyl group.

When the number of carbon atoms represented by R ³ is 1 to 6
Examples of alkyl groups of include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and hexyl.

In formula (VI), Y is an average value of 3 to 4, preferably 3.4 to 4, and most preferably 3.6 to 4.

The amount of component (B) useful in the alkoxy-functional RTV compositions of the present invention is based on the amount of other components added to satisfy the molar ratios (I) and (II) described below. Dependent. However, typically component (B) is present in an amount ranging from 0.1 to 0.1% based on the total weight of the alkoxy-functional RTV composition.
It is added in an amount of 5% by weight, desirably 0.5 to 3.0% by weight. The tetraalkoxytitanium compound is a single kind or a mixture of two or more kinds.

The alkoxy-functional RTV compositions of the present invention comprise a filler (c) having a hydroxyl content derived from covalently bonded hydroxyl groups, adsorbed water or both covalently bonded hydroxyl groups and adsorbed water. The term "covalently bonded hydroxyl group" as used herein means a hydroxyl group that is covalently bonded to a filler and used for a reaction. The term "adsorbed water" refers to the associated water on the surface of the filler utilized in the reaction and water from within the filler becoming available for the reaction.

Certain fillers have only adsorbed water and no covalent hydroxyl groups. However, many fillers have both covalent hydroxyl groups and adsorbed water, eg, untreated fumed silica fillers. The hydroxyl filler of the filler can be changed by drying the filler and / or pretreating the filler with a hydrophobic agent such as hexamethyldisilazane.

The filler is chosen from those known to be useful in alkoxy-functional RTV sealants. These fillers are ground, precipitated and colloidal calcium carbonate (which are untreated or treated with stearic acid or stearate); reinforcing silicas such as fumed silica, precipitated silica and hydrophobized silica. Crushed quartz, crushed quartz, alumina, aluminum hydroxide, titanium dioxide, diatomaceous earth, iron oxide, carbon black and graphite. Silica and calcium carbonate are particularly useful, and a mixture of fumed silica and treated ground calcium carbonate is desirable.

[0038] The amount of filler useful in the alkoxy-functional RTV composition depends on the viscosity, thixotropy, color and UV.
Provides the necessary properties of the uncured composition, such as protection. The amount of filler also depends on the required cured physical properties such as tensile strength, elongation and durometer.

The amount of filler useful in the alkoxy-functional RTV compositions of the present invention depends on the amount of other ingredients added, such that the molar ratios (I) and (II) described below are satisfied.
It also depends on the hydroxyl content of the particular filler used. However, typically the filler is added in an amount of 5-70% by weight, preferably 20-60% by weight, based on the total weight of the alkoxy-functional RTV composition.
The filler may be a single type or a mixture of two or more types.

The alkoxy-functional RTV composition of the present invention has the formula (VI): R ⁴ _z Si (OR ⁵ )
_4-z wherein each R ⁴ is independently selected from an alkyl group having 1 to 12 carbon atoms or an alkenyl group having 1 to 12 carbon atoms, and each R ⁵ is independently selected from methyl or ethyl. Z is 1 or 2].

The alkyl group having 1 to 12 carbon atoms represented by R ⁴ includes methyl, ethyl, isobutyl, hexyl, octyl and dodecyl. The alkenyl group having 1 to 12 carbon atoms represented by R ⁴ includes vinyl, allyl and butadienyl. Desirably, each R ⁴ is independently selected from the group consisting of methyl, ethyl, isobutyl and vinyl, with methyl being optimal. The subscript Z in Formula (IV) is 1 or 2, and 1 is desirable.

Examples of useful alkoxysilanes are methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, ethyltrimethoxysilane, octyltriethoxysilane,
Including dimethyldimethoxysilane, vinylmethyldimethoxysilane, dimethyldiethoxysilane, isobutyltrimethoxysila and ethylmethyldiethoxysilane.
Partial hydrolysates of these alkoxysilanes can also be used in the composition. Preferred alkoxysilanes include methyltrimethoxysilane and dimethyldimethoxysilane.

The amount of alkoxysilane useful in the alkoxylable RTV compositions of the present invention depends on the amounts of other components added to satisfy the molar ratios (I) and (II) described below. . However, typically, the alkoxysilane is added in an amount ranging from 0.1 to 10% by weight, preferably from 0.1 to 3% by weight, based on the total weight of the alkoxy-functional RTV composition. The alkoxysilanes can be used alone or as a mixture of two or more.

The molar ratio (I) is a value (sum) obtained by adding a mole of an alkoxysilane (component (D)) to a mole of a tetraalkoxytitanium compound (component B) and is a mole of the hydroxyl content in the filler (D). Defined as the divided value. Excellent storage stability is obtained when the inventive RTV composition has a molar ratio (I) of at least 0.9.
The molar ratio (I) of the preferred embodiment is in the range of 0.9-5, more preferably 1-3. Excellent stability is obtained when the molar ratio (I) is 5 or more, but other considerations make these compositions undesirable. For example,
Since the alkoxysilane and tetraalkoxysilane compounds are both molecules in molar ratio (I), having a ratio of 5 or more means increasing one or both of these components. However, increasing the amount of alkoxysilane decreases the cure rate, and increasing the amount of the tetraalkoxytitanium compound increases the cost of the composition and reduces the stability of the hydrolysis. Although the hydroxyl content in the filler can be reduced to lower the molar ratio denominator, it is not practical to reduce the hydroxyl content of the filler below a certain level.

The molar ratio (II) is obtained by adding the mole of the tetraalkoxytitanium compound (component B) to the mole of the alkoxysilane (component (D)) and the mole of the alkoxysilyl chain group in the polymer (component (A)). Is defined as the value divided by the sum The RTV composition of the present invention has at least 0.15
When the molar ratio (II) of the RTV composition is excellent, the tack free time is obtained, and the RTV composition cures quickly. The molar ratio (II) in the preferred embodiment is in the range of 0.2 to 0.6, more preferably 0.3 to 0.595. R of the present invention
Although TV compositions cure rapidly when the molar ratio (II) is greater than 0.6, other considerations make these compositions less desirable. For example, increasing the amount of the tetraalkoxytitanium compound increases the cost of the composition and reduces the stability of the hydrolysis. Moreover, the composition has a molar ratio (I
When I) is 0.6 or more, the composition rapidly cures, so that the working time after application of the composition is extremely limited, and the use of an automated robotic device is required.

The other ingredients commonly used in alkoxy-functional RTV compositions, such as adhesion promoters, rheology additives, fungicides, colorants, pigments and plasticizers, determine the ability of the composition to cure. It can be added initially or on storage provided that it does not interfere with the storage or reduce other necessary properties.

If the organofunctional trialkoxysilanes are used as adhesion promoters and their amounts are such that the molar ratio of the organofunctional trialkoxysilane is significantly higher with respect to the moles of alkoxysilane added, the molar ratio (I It is desirable to include the moles of such adhesion promoters as part of the moles of alkoxysilane in the determination of) and (II).

The alkoxy-functional RTV compositions of the present invention cure quickly. These results occur when the RTV composition consists of the tetraalkoxytitanium compound described by formula (V) and the molar ratios (I) and (II) are satisfied.

The present invention is further described by the following examples. “Parts” in the examples means parts by weight (indicated by “pbw”), and the viscosity was measured at 25 ° C. Me represents methyl, Et represents ethyl, “AS linkage” represents an alkoxysilyl linkage group, Ot-Bu represents tertiary butoxy, OnBu represents normal butoxy, OiP
r represents isopropoxy.

Component polymer used in Examples = Formula (where f has an average such that the viscosity of the polymer is 20 Pa · s)

[0051]

Embedded image Polydimethylsiloxane Titanium 1 = Average Formula Ti (Ot-Bu) _3.6 (OiP
r) mixture of titanium molecules with _0.4 titanium 2 = Ti (OiPr) ₄ titanium 3 = average formula Ti (OnBu) _3.72 (OiP
r) mixture of titanium molecules with _0.28 titanium 4 = average formula Ti (Ot-Am) _3.92 (OiP
r) mixture of titanium molecules having _0.08 alkoxysilane 1 = methyltrimethoxysilane alkoxysilane2 = dimethyldimethoxysilane silica filler = fume with a surface area of 150 m ² / g and an adsorbed water content of 0.6% by weight in Doshirika GRD CaCO ₃ = average particle size 2 to 3 [mu] m, surface treated with Sutearin'n acid, with ground calcium carbonate adsorbed water content of 0.05 wt% PPT CaCO ₃ = surface area of about ^22m 2 / g, stearic Precipitated calcium carbonate skin over time (SOT) surface treated with acid and having an adsorbed water content of 0.4% by weight

The skin overtime was 25 ° C and 5 ° C.
It is defined as the time required for the curing material to form a tack free surface film when exposed to atmospheric conditions at 0% relative humidity. The skin over time is measured by contacting the fingertip with the surface of the material and slowly pulling the fingertip apart. Skin over time is the time until the sample no longer adheres to the fingertip. The time is recorded in minutes.

Tack-Free Time (TFT) Tack-free time is defined as the time required to form a tack-free surface film, but this test uses contact of a polyethylene film to measure tack-free properties. A clean polyethylene strip is applied to the test surface with light fingertip pressure. The strip is then removed from one end by gently pulling it straight up. The tack free time is the time until the strip cleanly leaves the sample. The test is performed under atmospheric conditions at 25 ° C. and 50% relative humidity. The tack free time is stated in minutes.

Examples 1 to 4 Four alkoxy-functional RTV sealant compositions were each prepared using the ingredients shown in Table 1 under moisture blocking conditions. The compositions were prepared by first adding the alkoxysilane and titanium compound to the polymer, mixing, adding the filler, mixing and drawing a vacuum to remove entrained air. The moles of the groups and components are RT
100 g of V sealant composition and Table 1
In parentheses below the weight parts. In this specification, the defined molar ratios (I) and (II) have been determined using the molar values given. The alkoxy-functional RTV sealant composition was stored in a sealed container protected from atmospheric moisture. Initial tests were performed after storage at 25 ° C. for 7 days. The samples were then aged at 50 ° C. for a further 7 days before retesting. Cure times were tested as described above, and the results are shown in Table 1. Examples 1 and 4 were initially and 50 ° C. using titanium 1 and titanium 4, respectively, as compared to SOT and TFT obtained using titanium 2 and titanium 3 outside the scope of the present invention. Indicates excellent SOF and TFT after storage for one week.

[0055]

Table 1-Use of different tetraalkoxy titanium compounds

Examples 5 to 9 RTV containing titanium 1 in the same manner as in Examples 1 to 4
Sealant compositions were prepared and tested. Those ingredients,
The amounts and the properties measured are shown in Table 2. Comparative Examples 5 and 7
Indicates the criticality at the lower end of the molar ratios (I) and (II) of the fast-curing composition and the storage-stable composition.

[0057]

Table 2-Compositions containing titanium 1 in various molar ratios

Examples 10-11 RTV containing titanium 4 in the same manner as in Examples 1-4
Sealant compositions were prepared and tested. Those ingredients,
The amounts and the properties measured are shown in Table 3. Comparative Example 10 shows the criticality at the lower end of the molar ratio (II) of the fast-curing composition.

[0059]

Table 3-Compositions containing titanium 4 in various molar ratios

Examples 12-15 RTV sealant compositions were prepared and tested in the same manner as in Examples 1-4. The components, amounts and measured properties are shown in Table 4. Example 14 shows excellent cure rates using different fillers. Comparative Examples 12 and 13 show the lower criticality of the molar ratios (I) and (II) for cure speed using this different filler. Example 15
Indicates that a fast-curing composition is obtained using an alkoxysilane having an alkoxy group.

[0061]

Table 4-Action of different fillers or alkoxysilanes

Claims (6)

[Claims] 1. A moisture-curable, alkoxy-functional natural vulcanizing composition comprising the following components (A) to (D): (A) Formula -SiR1x (OR) 3-x (VII) Wherein each R is independently selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and isobutyl; R1 is selected from methyl or ethyl; x is 0 or 1 A) a polymer having an average of at least 1.2 alkoxysilyl chain terminators per molecule described by: (B) a formula Ti (OR2) y (OR3) 4-y (V), wherein each R2 is Tertiary alkyl group or 2,4-dimethyl-
Independently selected from 3-pentyl; each R3 is independently selected from alkyl groups having 1 to 6 carbon atoms; y is an average of 3 to 4); A) a filler having a hydroxyl content derived from covalently bonded hydroxyl groups, adsorbed water, or both covalently bonded hydroxyl groups and adsorbed water; and (D) a formula R4zSi (OR5) 4-z (VI) wherein Each R4 is independently selected from an alkyl group having 1 to 12 carbon atoms and an alkenyl group having 1 to 12 carbon atoms; each R5 is independently selected from methyl or ethyl; and Z is 1 or 2. Wherein the components (A), (B), (C) and (D) have the following molar ratio (I) of at least 0.9 and a molar ratio (II) of 0 .15- Is added in an amount such that the range of .6: 2. The alkoxylizable natural according to claim 1, wherein the molar ratio (I) is in the range from 1 to 3 and the molar ratio (II) is in the range from 0.3 to 0.595. Vulcanized composition. 3. The alkoxy functional spontaneous additive according to claim 2, wherein each R2 is a tertiary butyl group or a tertiary amyl group, respectively, and Y is an average value of 3.6-4. Sulfuric acid composition. 4. Component (A) is a compound of formula (I) And mixtures of the polydiorganosiloxanes described by formula (I) and formula (II) Wherein each R6 is independently selected from the group consisting of methyl, ethyl and vinyl; and R9 is an alkyl, phenyl and fluorinated alkyl group having 1 to 6 carbon atoms. Independently selected from the group consisting of:
A viscosity in the range of ３3000 Pa · s]. 5. Component (A) is a compound of formula (III) [Wherein each R9 is an alkyl group having 1 to 6 carbon atoms,
F is independently selected from the group consisting of phenyl and fluorinated alkyl groups;
Has a value such that it has a viscosity in the range of 00 Pa · s;
Each Z is a divalent hydrocarbon group having 2 to 18 carbon atoms containing no aliphatic unsaturation or a combination of divalent hydrocarbon groups, and formula (Wherein R 9 is as defined above; each G is a divalent hydrocarbon group containing 2 to 18 carbon atoms without aliphatic unsaturation; c is a total of 1 to 6). Independently selected from the group consisting of siloxane segments of the formula (I). 6. Component (A) is of the formula (III) Or a mixture of polypolydiorganosiloxanes described by formula (III) and formula (IV) An alkoxy-functional natural vulcanization composition according to claim 2 consisting of a polydiorganosiloxane described by Wherein each R9 is independently selected from the group consisting of alkyl groups having 1 to 6 carbon atoms, phenyl groups and fluorinated alkyl groups; 3000
Has a value such that it has a viscosity in the range of Pa · s;
Is a divalent hydrocarbon group containing no aliphatic unsaturation and having 2 to 18 carbon atoms or a combination of divalent hydrocarbon groups, and a formula (Wherein R 9 is as defined above; each G is a divalent hydrocarbon group containing no aliphatic unsaturation and having 2 to 18 carbon atoms; c is a total number of 1 to 6). Independently selected from the group consisting of siloxane segments.